What Is Obstructive Sleep Apnea (OSA)

Obstructive Sleep Apnea as Defined by the American
Sleep Apnea Association

The Greek word "apnea" literally means "without breath." There are three types of apnea: obstructive, central, and mixed; of the three, obstructive is the most common. Despite the difference in the root cause of each type, in all three, people with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night and often for a minute or longer.

Obstructive sleep apnea (OSA) is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses and closes during sleep. In central sleep apnea, the airway is not blocked but the brain fails to signal the muscles to breathe. Mixed apnea, as the name implies, is a combination of the two. With each apnea event, the brain briefly arouses people with sleep apnea in order for them to resume breathing, but consequently sleep is fragmented and of poor quality.

Sleep apnea is common affecting more than twelve million Americans, according to the National Institutes of Health. Risk factors include being overweight and over the age of forty, but sleep apnea can strike anyone at any age, even children. Yet still because of the lack of awareness by the public and healthcare professionals, the vast majority with sleep apnea remain undiagnosed and therefore untreated.

Untreated, sleep apnea can cause high blood pressure and other cardiovascular disease, memory problems, weight gain, impotency, and headaches. Moreover, untreated sleep apnea may be responsible for job impairment and motor vehicle crashes. Fortunately, sleep apnea can be diagnosed and treated. Several treatment options exist, and research into additional options continues.

Most people with sleep apnea have obstructive apnea, in which the person stops breathing during sleep due to airway blockage. Sufferers usually resume breathing within a few seconds, but periods of as long as sixty seconds are not uncommon in serious cases. It is more common amongst people who snore, who are obese, who consume alcohol, or who have anatomical abnormalities of the jaw. Atypical cases do occur, and the condition should not be ruled out merely because the patient does not fit the profile.

"OSA" is caused by the relaxation of the muscles in the airway during sleep. While the vast majority of people successfully maintain an open upper airway and breathe normally during sleep, a significant number of individuals are prone to severe narrowing or occlusion of the pharynx impeding breathing. As the brain senses a build-up of carbon dioxide, airway muscles are activated which open the airway, allowing breathing to resume but interrupting deep sleep.

These recurrent episodes of airway obstruction are associated with asphyxia, hypertension, depression, and daytime fatigue, since a transient interruption of the sleep cycle accompanies the restoration of airway air flow. Most sufferers are not aware of these events, and are informed of the symptoms by their sleep partner. The apneic episodes are thought to account for the clinical symptoms that arise from a particular condition, which include increased incidence of chronic hypertension, a 700% rise in road traffic accidents, excessive daytime somnolence, social and family disruption, and cardiac arrhythmias and morbidity.